Vapor electric device



Aug. 19, 1947. w, PAKALA 2,426,046

VAPOR ELECTRIC DEVICE Filed Au 11, 1942 4 Potentml Time Po'lentia 7 WITNESSES: INVENTOR William E. Paka la.

I 3M 1M ATTORNEY Patented Aug. 19, 1947 2,426,046 VAPOR ELECTRIC DEVICE William E. Pakala, Westinghouse Electric Forest Hills, Pa.,

Corporation,

assignor to East Pittsburgh, Pa., a corporation of Pennsylvania Application August 11, 1942,

Serial No. 454,372

Claims. (01. 315-166) My invention relates to a vapor-electric device and particularly to an excitation system for improving the operating characteristics of a vaporarc valve device.

In the operation of vapor-arc valve devices, two types of excitation have heretofore been utilized. The first, and for many years, the standard excitation system, has been a system substantially constant, continuous excitation of a value suflicient to secure pickup of the arc to any positive anode. Usually the actual time of pickup was controlled by means of a suitable shield and grid system. The second method of excitation is the recently invented make-alive type in which the cathode spot is not maintained but reinitiated at the beginning of each conducting half cycle.

With the first method of excitation, it was necessary to maintain a heavy protective grid system in order to reduce the probabilities of are back during This heavy grid system resulted in excessive arc drop losses in the valve device. When the make-alive system is utilized, the shielding could be reduced to a minimum but the requirements of striking the cathode spot and producing the necessary vapor to insure pickup required excessive impulse energy.

In the excitation system according to my invention, a continuous excitation current is provided of sufiicient intensity to maintain a cathof too low intensity to maintain produce pickup, and a periodic current impulse is superimposed on the continuous excitation to produce the necessary ionization to secure pickup at the beginning of each conducting half-cycle.

It is accordingly an object of my invention to provide an excitation circuit having improved operating characteristics. It is a further object of my invention to provide an exciting system requiring the minimum of excitation energy to secure reliable operation.

It is a further object of my invention to provide a direct-current excitation system having an alternating-current impulse superimposed thereon.

Other objects and advantages of my invention will be apparent from the following detailed description taken in conjunction with the accompanying drawing, in which:

I Figure 1 is a schematic illustration of a vapor- .electricsystem according to my invention.

' Figs. 2,3 and dare graphical illustrations of the component currents and resulting excitation current secured by my excitation system.

In the illustrative embodiment of my invention, an alternating-current circuit 10 is connected to a direct-current circuit II by means of a suitable transformer means l2 and the flow of current through the transformer I2 is controlled by means of a plurality of vapor-electric valves 13. Each of the vapor-electric valves l3 comprises a main anode l4 and cathode IS within an evacuated container IS. The anode I4 is preferably surrounded by a suitable shield l1. Also each valve I3 is provided with a starting electrode 20 herein resistant make-alive type and a suitable keepalive electrode 2!. The starting electrode 20 and the keep-alive electrode 2| are preferably connected in parallel to a suitable source of continuous exciting current herein shown as a full wave rectifier 22 fed from a suitable alternating-current source such as the alternating current line H].

While any suitable number of valves l3 may be utilized, I have herein shown a pair of alternately conducting valves 13, while it is apparent that any number of pairs of valves l3 may be utilized each pair having a similar excitation system. In order to divide the direct-current between the pairs of exciting electrodes 2|, a high reactance 23, preferably of the coil type, is inserted between the pair of exciting electrodes 2|, the positive side of the direct-current source 22 being connected to a mid tap 24 of the reactor 23 the other side of the direct-current source 22 being connected to the cathodes 15 of the valves l3. In order to secure a periodic alternating current impulse, I have provided a wave distorter impulsmg system herein shown as of the reactor type, while it is obvious that any suitable impulsing device may be utilized. The preferred wave distorter system comprises a source 25 of alternating current having a capacitor 26 connected across its terminals and a suitable impedance 21 for controlling the flow of current from the alternating-current source 25 to the capacitor 26. A voltage sensitive variable reactor 28 is inserted between the alternating-current source 25 including the capacitor 26 and the excitation electrodes, 26 and 2| to control the flow of current from the source 25 to the electrodes 20 This voltage sensitive impedance 28 is usually in the form of a saturable reactor which, at low voltages, offers a very high impedance to the flow of current, but when saturating potential is supplied a satin the reactor and rea urating current fioWs duces its impedance to and returns through the cathode connection to 7 Then at the instant on right-hand valve l3. Unless the negative'impulse is bypassed it attempts toflow through the electrodes 2'0-2! of the right-hand valve I3, and reduces the total current to such a value as to interrupt current flow to electrode 2|-of the right-hand valve I 3. In order to prevent reverse current flow through the exciting electrodes Zlland 2| which receives 7 polarity sensitive circuit isprovided in shunt with the exciting electrodes Preferably this polarity sensitive shunt 30 is in the form of a unidirectional conductor such as a dry rectifier.

In order to control the time instant of the application of the ionizing impulse, I prefer to providea suitable phase shifting device 3| in series With the alternating-current source 25. I also prefer to provide alive electrode 2|. In this electrode 2!] will operate only until such time as mum positive potentialat the time of the ionizing impulse as shown in Cox et al., Patent 2,259,293.

pair of valves l3, and at ,the proper interval a current impulse 4| 'will bedelivered to one of the starting electrodes 20. This current impulse 4| will be sufiiciently high tolinitiate 'a cathode spot after which the current will pickup to the keep-alive electrode 2| and the flow of current to the keep-alive electrode 2| will open the circuit interrupting device 35 in series with the starting electrode 20. The other half-cycle from While I have shown and described a specific embodiment of my invention, it will be apparent I claim as my invention:

1. An electric current translating system interconnecting a direct-current circuit and an alternating-current circuit comprising-at-least a current -be tween the mid-point of said reactor-and the cathodes of said valves.

2. An electric current translating system interconnecting a direct-current circuit and an valve, a keep-alive electrode in each valve-a source of alternating potential, circuit means including a saturable reactor for connecting said source of alternating-current potential to said starting electrodes and said keep-alive =elec- 3. An ignition system fora vapor-electric valve comprisin a, starting electrode in-said valve, an

starting electrode.

4. An electric current translating system -for interconnecting a direct-current circuitand-an alternating-current circuit opposite terminals of -said-alternating-current source to the exciting electrodes of the-respective valves, a source of direct current; a reactor-connected across the output terminals of said circuit, a tap intermediate the ends of said reactor and circuit means for impressing the potential of said source of direct current between said tap and the cathodes of said valves.

5. An electric current translating system for interconnecting a direct-current circuit and an alternating current circuit comprising a pair or alternately conducting vapor-electric valves, each valve including a main anode and cathode and exciting electrodes including an electrode in contact with the cathode and an electrode spaced from the anode and cathode, a source of alternating-current potential, a circuit for connecting opposite terminals of said alternating-current source to the exciting electrodes of the respective valves, a source or direct current, a reactor connected across the output terminals of said circuit, a tap intermediate the ends of said reactor and circuit means for impressing the potential of or direct current between said tap or said valves, circuit interrupting means in series with the electrodes in contact with the cathodes and means energized by current flow to the associated spaced electrode for actuating said circuit interrupting means.

6. An exciting system for a vapor-electric valve comprising a source of substantially constant direct current, a source of alternating current, wave distorter means for producing periodic current impulses of short duration from said alternatingcurrent source, a startin electrode in said valve, an exciting electrode in said valve, and connections for impressing said direct current and said current impulse in parallel on said electrodes, and phase shifting means between said source of alternating current and said wave distorter means.

'7 An ignition system for a vapor-electric valve comprising a keep-alive electrode in said valve, a source of direct current exciting potential, means for connecting said source of direct current to said keep-alive electrode, the potential of said source of direct current potential being sufficient to normally maintain a keep-alive arc in said valve, a source of periodic potential, a makealive electrode in said valve, means for connecting at least said source of periodic potential to said make-alive electrode for initiating excitation in said valve and means for impressing the potential of said source of periodic potential on said keep-alive electrode for periodically re-enforcing the excitation in said valve.

8. An ignition system for a vapor-electric valve comprising an exciting electrode in said valve, a source of direct current exciting potential, means for connecting said source of direct current to said exciting electrode, the potential of said source of direct current potential being sufficient to normally maintain a keep-alive arc in said valve, a source of periodic potential and means for impressing the potential of said source of periodic potential on said exciting electrode for periodically re-enforcing the excitation in said valve, a starting electrode in said valve and means responsive to current flow to said exciting electrode to determine the energization of said starting electrode.

9. An exciting system for a vapor-electric valve comprising a. source of substantially constant direct current, a source of alternating current, wave distorter means energized from said source of alternating current for producing periodic impulses of short duration, a starting electrode in said valve, means for impressing the impulses of short duration on said starting electrode for initiating exci ation in said valve, an exciting electrode in said valve, connections for impressing the potential of said source of direct current on said exciting electrode for maintaining a keepalive arc of low intensity in said valve and means for impressing the output of said wave distorter means on said exciting electrode for periodically increasing the intensity of excitation in said valve.

10. An exciting valve comprising a source of substantially constant direct current, a source of alternating current, wave distorter means energized from said source of alternating current for producing periodic impulses of short duration, an exciting electrode in said valve, connections for impressing the potential of said source of direct current on said exciting electrode for maintaining a low degree of excitation in said valve and means for impressing the output of said wave distorter means on said exciting electrode for periodically increasing the degree of excitation in said valve, a starting electrode in said valve and switching means responsive to current flow to said exciting electrode for controlling the energization of said starting electrode.

WILLIAM E. PAKALA.

REFERENCES CITED The following references are of record in the 

